1. Field of the Invention
The present invention relates to a test strip for measuring tear production, which is used by an ophthalmologist to measure the tear production of a patient to diagnose a disease or any other abnormality of the eye.
2. Prior Art
Known test strips for measuring tear production include the Shirmer tear test strip which has a width of about 5 mm and a length of 42 mm, with its one end rounded to be semi-circular shaped, and having a triangular notch at one side of the strip spaced by about 5 mm from the rounded end. The Shirmer tear test strip is used by inserting the rounded end internally into the lower eye-lid of a patient with the rounded end bent at the notched portion, and the test result is evaluated by visually determining the length of the moistened filter paper wetted within a unit measurement of time.
However, the prior art Shirmer tear test strip has a disadvantage in that the notched portion tends to contact the eyeball or interior surface of the lower eye-lid which causes cause irritation or complaint, since the strip is bent at the notched portion and then inserted internally into the lower eye-lid. The prior art Shirmer tear test strip has another disadvantage in that the moistened strip tends to break during the measurement operation since the width of the strip is narrowed by the notch. A further disadvantage of the prior art Shirmer tear test strip is confusion in determining whether a particular strip is used for the testing of the right or left eye of the patient, this being caused by difficulty in determination of obverse or reverse side of the filter paper. In addition, visual determination often leads to an inaccurate diagnosis, or a separate scale must be used for precise determination which incurs delicate operation and inconvenience in practical application.